chromium/third_party/angle/src/libANGLE/Observer.h

//
// Copyright 2016 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Observer:
//   Implements the Observer pattern for sending state change notifications
//   from Subject objects to dependent Observer objects.
//
//   See design document:
//   https://docs.google.com/document/d/15Edfotqg6_l1skTEL8ADQudF_oIdNa7i8Po43k6jMd4/

#ifndef LIBANGLE_OBSERVER_H_
#define LIBANGLE_OBSERVER_H_

#include "common/FastVector.h"
#include "common/angleutils.h"
#include "libANGLE/Constants.h"

namespace angle
{
template <typename HaystackT, typename NeedleT>
bool IsInContainer(const HaystackT &haystack, const NeedleT &needle)
{ … }

SubjectIndex;

// Messages are used to distinguish different Subject events that get sent to a single Observer.
// It could be possible to improve the handling by using different callback functions instead
// of a single handler function. But in some cases we want to share a single binding between
// Observer and Subject and handle different types of events.
enum class SubjectMessage
{ … };

inline bool IsProgramUniformBlockBindingUpdatedMessage(SubjectMessage message)
{ … }
inline SubjectMessage ProgramUniformBlockBindingUpdatedMessageFromIndex(uint32_t blockIndex)
{ … }
inline uint32_t ProgramUniformBlockBindingUpdatedMessageToIndex(SubjectMessage message)
{ … }

// The observing class inherits from this interface class.
class ObserverInterface
{ … };

class ObserverBindingBase
{ … };

constexpr size_t kMaxFixedObservers = …;

// Maintains a list of observer bindings. Sends update messages to the observer.
class Subject : NonCopyable
{ … };

// Keeps a binding between a Subject and Observer, with a specific subject index.
class ObserverBinding final : public ObserverBindingBase
{ … };

}  // namespace angle

#endif  // LIBANGLE_OBSERVER_H_